1. Field of the Invention
The present invention relates to an image forming apparatus and a method, and in particular, to a recording material determination apparatus and method for detecting reflected light from a surface of a recording material and determining a kind thereof, and an image forming apparatus and method using the recording material determination apparatus.
2. Description of the Related Art
An image forming apparatus such as a copying machine or a laser printer transfers an image visualized and developed by a development portion on a recording material and heats and pressurizes it under predetermined fixing conditions so as to fix a developed image. The predetermined fixing condition is significantly different depending on quality, thickness and surface treatment of the recording material. Therefore, a detailed setup according to a kind of recording material are required when using a plurality of kinds of recording material.
Conventionally, such an image forming apparatus has a size and a kind (kind of paper in the case where the recording material is paper) of recording material set up by a user on an operation panel provided on the image forming apparatus proper for instance so as to change the fixing conditions (fixing temperature and feeding speed of the recording material passing through a fixing apparatus for instance) according to that setup. Or else, there is a proposed method of having control means for setting it at a temperature lower than normal temperature and thereby solving adverse problems such as OHT twining on a fixing roller occurring in case of having an inkjet OHT (Over Head Transparency) other than prescribed paper mistakenly put through by the user and image degradation on a recording medium (refer to Japanese Patent Application Laid-Open No. 2003-228256 for instance).
There is also a known method, not limited to the OHT, of calculating depth of asperities and asperity intervals on a recording medium surface from a result of reading a surface image of the recording medium and determining the kind of recording medium such as gloss paper, plain paper, rough paper or OHT so as to optimally set image forming conditions including printing density, transfer bias setup, fixing temperature and process speed (refer to Japanese Patent Applications Laid-Open Nos. 2003-302208 and 2001-225988 for instance).
Such image reading apparatuses mostly have degradation of shot images due to variations in light volume caused by a light source or a lens. There are also variations in sensitivity in photoelectric cells of an image pickup device. For this reason, there is a thinkable method, for the sake of accurately reading an object and obtaining a correct imaging result, of shooting for measuring a shading amount a plurality of times in a state of having the recording medium moved and averaging shooting results thereof so as to automatically calculate the shading amount and correct the shooting results.
In the case of the above-mentioned image forming apparatus, however, it is necessary to shoot a plurality of times in the state of having the recording medium moved. For that reason, there is a problem that a sufficient area for having the recording medium moved must be secured in the image forming apparatus and so the apparatus becomes large.